The U.S. House Appropriations Committee report said the F-35 Joint Strike Fighter program, the largest Pentagon weapon program ever, would lose $1 billion in 2013 -- and four jets. (Lockheed Martin)

Unless lawmakers find a way to prevent a $53 billion cut to planned defense spending for 2013, the U.S. military services would be forced to buy fewer F-35 fighters, Stryker vehicles and Army helicopters, says a House panel. What’s more, the pending cut could jeopardize the Air Force’s plans for new tanker and bomber fleets.

The report, released Oct. 9 by House Appropriations Committee (HAC) Democrats, offers the first projections of how many big-ticket weapon systems the armed services likely would cut under the first tranche of a decade-long spending cut.

The Air Force would take a major hit under that first year of a broader 10-year, $500 billion reduction to planned Pentagon spending. The service would be forced to slash funding for its KC-46 aerial tanker program by $99.5 million next year, a move the lawmakers conclude would slow the program’s crucial engineering and development phase. Boeing is the prime contractor on that high-profile program.

The air service also would have to slash by $33.7 million its 2013 budget for an initiative to design and field a new bomber aircraft.

The largest Pentagon weapon program ever, the F-35 fighter effort, would lose $1 billion in 2013 — and four jets. Lockheed Martin is the prime contractor.

The panel predicts the Army would be forced to buy eight fewer Sikorsky-made Black Hawk helicopters and five fewer Boeing-made CH-47 Chinook choppers. Collectively, those moves would “[slow] Army plans to modernize its utility and heavy lift helicopter fleet,” the panel’s Democrats write in the “dear colleague” report, sent to all members of Congress.

The Army also would have to purchase 11 fewer General Dynamics-made Stryker vehicles, the HAC Democrats say, adding that would hurt the service’s “ability to keep Stryker brigades fully outfitted.”

The report bears the signature of soon-to-retire Rep. Norm Dicks, D-Wash., the outgoing House Appropriations Committee ranking member. (He holds the same seat on the panel’s powerful Defense subcommittee.)

The Navy would buy two fewer Boeing-made F-18G electronic warfare aircraft and three fewer F/A-18E/F Super Hornets. The latter move, the lawmakers say, would make “if more difficult to avoid a carrier-based strike fighter shortfall.”

Boeing would take a further hit because the Navy likely would kill one planned P-8A aircraft, which conduct surveillance and electronic warfare, the report states.

The planned spending cuts, which would occur under a process known as sequestration, also would hit America’s nuclear arms arsenal.

“The National Nuclear Safety Administration (NNSA) would also be subject to the more substantial defense reduction. Under sequestration, NNSA Weapons activities would be cut by $861 million,” the report states. “With this reduced budget, NNSA would no longer be able to support modernization of the weapons complex, including required life extension programs to ensure the nation’s nuclear deterrent remains safe, reliable and effective.”

Also hit hard would be the Pentagon’s operations and maintenance accounts, which would take a $1.6 billion cut next year.

“This reduction would limit DOD’s ability to maintain and modernize key weapon systems, and overhaul weapons systems damaged in operations,” the HAC Democrats state. “Sequestration would severely degrade the Defense Department’s ability to maintain a trained and ready force, and would similarly ensure that the condition of combat equipment and military facilities would deteriorate.”

The report surely will be used by both sides of the defense spending debate in coming weeks and months.

“It is encouraging to see Democrats actually being open about the impact of sequestration to defense,” one House Republican source said. “It’s interesting to see the discordant messages from Democrats, with Norm Dicks’ message that sequestration would hurt defense and cause millions of job losses, and then the message from OMB that it won’t. … Members need to understand how deeply this would hurt defense.”

“Rather than a discordant message it is entirely consistent: the committee report underscores the harm that sequestration could do to our economy if the Republicans’ intransigence prevails in order to preserve tax cuts for high-income taxpayers,” said Ryan Nickel, spokesman for the House Appropriations Committee’s Democratic members.

Not everyone in the defense sector agrees, however.

“After an unprecedented 13 straight years of increases in base defense budgets, the Pentagon is well positioned — even for sequestration-size cuts,” Lawrence Korb, a former Pentagon official now with the Center for American Progress, wrote in a recent op-ed. “Such reductions would return the country to its fiscal year 2006 level of defense spending, when the United States was fighting two large land wars.”

On the matter of how many job losses the cuts would spawn, there is ample disagreement. A study commissioned by a defense trade association that is being used by GOP nominee Mitt Romney’s campaign warns of over 1.2 million lost jobs just from defense cuts. Other studies have panned that one for failing to factor in important economic elements, such as whether dollars not spent on the military might be spent in other sectors, thus creating new jobs.

But a Congressional Research Service (CRS) report that surfaced just hours before the HAC Democrats’ released their study questioned the findings of each of the jobs-related estimates.

“Any projections involve considerable uncertainty and thus margins for error,” the CRS report states. “State-by-state job impacts of the analyses — which appeared to garner the most attention — were based on the perhaps unlikely assumption that the distribution of program spending by industry in the past would continue in the forecast period.”

The final passage of the Dicks-signed report offers a window into the policy differences that have so far prevented Democrats and Republicans from agreeing to the necessary $1.2 trillion deficit-reduction plan that would void the defense cuts and a twin $500 billion cut to planned domestic spending over the same span.

“Congress must find a way to replace sequestration with a balanced approach to long-term deficit reduction that focuses on economic growth and job creation, and does no harm to our economic recovery in the short-run,” the Democrats’ report states.

The operative term is “balanced approach,” Democratic code for a deficit-reduction plan that includes spending cuts, entitlement program reform, defense cuts and tax hikes for the wealthiest Americans. Most congressional Republicans, however, oppose the final two legs of such a plan.